The present invention relates generally to monitoring and/or controlling an electric cooktop, and, more particularly, to a system for generating control signals responsive to properties of a cooking utensil detected through a solid surface cooktop.
Recently, standard porcelain enamel cooktop surfaces of domestic ranges have been replaced by smooth, continuous-surface, high-resistivity cooktops located above one or more heat sources, such as electrical heating elements or gas burners. The smooth, continuous-surface cooktops are easier to clean because they do not have seams or recesses in which debris can accumulate. The continuous cooktop surface also prevents spillovers from coming into contact with the heating elements or burners. Exemplary cooktops comprise glass-ceramic material because of its low coefficient of thermal expansion and smooth top surface that presents a pleasing appearance.
Devices are known for detecting the presence of a utensil on a cooking appliance, such as those dependent on contact with the cooking utensil disposed on an electric heating element or on the utensil support of a gas burner. Such contact-based systems, however, have not proven to be feasible for continuous-surface cooktops, and especially glass-ceramic cooktops due to the difficulties of placing contact sensors thereon. Cooking utensil contact sensors generally disrupt the continuous cooktop appearance, weaken the structural rigidity of the cooktop, and increase manufacturing costs. Also, such contact-based systems are not inherently reliable on smooth-surface cooktops because cooking utensils with warped or uneven bottoms may exert varying forces on the contact sensors and give a false contact indication.
Accordingly, it is desirable to provide a system for detecting cooking utensil characteristics or utensil-related, through-the-cooktop-surface properties, such detection being independent of a cooking utensil's composition, flatness of bottom, or weight. It is further desirable that such a system generate energy source control signals based on detecting through the glass-ceramic cooktop the presence/absence, removal/placement, or size of a cooking utensil on the cooktop.